The present invention relates to ground-penetrating radar (GPR) systems and methods, and more particularly to ground-penetrating radar systems and methods for identifying buried objects.
GPR is similar to upward-looking radar used for air traffic control and meteorology, except that the antenna array is directed toward the ground; thus presenting an entirely different set of technical challenges. For example, GPR is used for geophysical applications such as mapping sub surface strata, locating toxic waste sites for rededication, and detecting of unexploded sub surface ordinance.
A GPR system comprises at least one transmitter that transmits an electromagnetic impulse, continuous wave, or swept frequency signal, for example, in the frequency range of 1 MHz to 10 GHz. The system also comprises at least one receiver that receives a reflected waveform. The impulse is short with respect to the wavelength being transmitted. In practice, the impulse can be, for example, one or two cycles. Therefore, GPR systems are sometimes referred to as xe2x80x9cimpulsexe2x80x9d radars.
Sub surface industries such as construction, utility location, environmental rededication, and unexploded-ordnance detection have long sought safe, reliable, cost-effective methods for xe2x80x9cseeing into the ground.xe2x80x9d The utility location market suffers greatly from inadequate location technologies that result in hundreds of millions of dollars in damages, delays, and lost revenue for utility companies and contractors every year, losses that can be reduced significantly by use of GPR. Three utility locating market segments, can be distinguished by their accuracy and price: (1) One Call; (2) private locating; and (3) sub surface utility engineering (SUE).
xe2x80x9cOne Callxe2x80x9d is a nationwide clearinghouse that provides an alert to all public and private utilities of when and where construction may impact their lines. By law, contractors must register their site with One Call, which in turn contacts all the relevant utilities so they can mark their utility lines. One Call locating systems are based on electromagnetic induction technology. Utility companies, responding to a One Call work order, guarantee accuracy on conductive lines within twenty-four inches horizontally on either side, with no guarantee of depth. With One Call, utility line locations are simply painted temporarily on the ground, easily subject to erosion or destruction. This poor accuracy results in broken utility lines and revenue loss.
Construction, utility, and industrial companies often rely on xe2x80x9cprivate locating.xe2x80x9d Private locating provides a greater degree of accuracy than is delivered by One Call. These companies often hire a utility locating company or a geophysics company to apply more expensive and time-consuming locating techniques. Private locating companies typically use electromagnetic induction technology, GPR, and magnetometer. Often this includes excavation, the most reliable and expensive conventional method for determining the exact location of utilities.
Industrial and utility companies, however, frequently require more accurate maps of the sub surface than One Call or private locating can provide. For instance, extra accuracy may be needed while excavating near an oil pipeline because of the rise of breaking a pipe. Or, it may be too costly to accidentally cut an interstate fiber optic cable carrying important communications. In such situations, excavators perform a total cost/value analysis, including consideration of risk/cost avoidance. Often, they are more willing to pay higher fees to ensure greater accuracy.
xe2x80x9cSUExe2x80x9d can provide more accuracy than One Call or private locating. SUE is a rapidly growing specialty service offered by geophysical and engineering companies. It entails planning and designing utility arrangements before highway or other large infrastructure construction. SUE engineers painstakingly map all discernible utilities at a given site using a variety of conventional geophysical methods. SUE uses electromagnetic induction technology, GPR, and magnetometer. It is generally more costly than private locating services because it uses computer aided design to produce a permanent record of the location of utilities. Even this premium service often only identifies 80% of utilities with certainty, frequently less when unknown non-conductive utilities are present. Further, SUE is very expensive. Accordingly, there is, therefore, a need for systems that overcome the limitations of the conventional techniques.
The present invention provides a methodology for identifying buried objects using ground penetrating radar. Additional features and advantages of the invention will be set forth in the description which follows, and in part, will be apparent from the description, or may be learned by practicing the invention. The objectives and other advantages of the invention will be realized and obtained by the method and apparatus particularly pointed out in the written description and the claims hereof as well as in the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the invention, as embodied and broadly described, an apparatus and method according to the invention identifies buried objects using GPR. An apparatus for identifying a buried object using ground penetrating radar (GPR) in a system containing at least one GPR sensor, comprises a data processor for detecting spatial correlations in data received from a GPR sensor in the apparatus and an image processor capable of building a data structure corresponding to an image of the buried object from data processed by the data processor. A method for identifying a buried object using GPR in a system containing a GPR sensor comprising detecting spatial correlations in data received from the GPR sensor in the system and building a data structure corresponding to an image of the buried object from the received data.
Both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.